Bass Bin Coupling

[Larry M]

I’m a mobile DJ and want to get the best sound from my 4 active subs and need clarification and set up advise.

I currently use 2 to 4 active 15” subwoofers that also provide the amplification to the top boxes. The system is crossed over at 180hz and cannot be changed. It’s an all in one set up that does not have any user settings besides gain.

I always set up the subs side by side and the tops spread out to the right and left on tri-pods. This configuration sounds really good to me and better then the subs spread apart underneath the tops. Now when I add two more of the same exact subwoofers for a total of 4 I need your advise on how to set the 4 up.

I have positioned them in a horizontal row of 4 but if I’m understanding coupling correctly, does this mean my subs that are crossed over at 180hz would need to be no more than about 18.75” apart from the center of each cone to achieve coupling without cancellation or any negative effects. This is a very close distance as the subs are crossed over very high. The first two subs are close but the end subs would be farther than my estimated 18.75” from each other.

I have also put the subs in a cluster of 4 and it appears the diagonal distance is also farther than 18.75” Would setting up 2 subs on each side of my set up under the tops with a minimum distance of 12.5’ be a better solution?

I would really like to hear an explanation on the best placement for my particular situation using the mentioned 4 subs.

[Bill Fitzmaurice]

One wavelength at 180Hz is 6.25 feet. One wavelength is what you use for center to center, which mainly applies to midrange and high frequency sources. With subs it's 1/4 wavelength from cabinet edge to cabinet edge.

[Larry M]

Bill, Thank you for the quick reply and clarification! So if I divide one wavelength by 4 this equals 1.56 feet. With this length the only way that I can achieve this with four cabinets is in a cluster configuration.

This brings me to my next question. The subs port is across the entire length of the bottom of the cabinet. What orientation should the subs be placed? A cluster of four on their sides with the ports touching each others from top cab to bottom cab? or a cluster of four with the subs standing vertically side by side?

[Bill Fitzmaurice]

That's 1.56 feet from cab edge to cab edge. That shouldn't be a problem. The port orientation doesn't matter.

[Bruce Weldy]

So, what kind of boxes are these? The crossover point sounds like a Bose L series, but then you said you put the tops on stands, so that rules that out.......

[Larry M]

Thank you! Now that I have a plan when using four subwoofers I can now experiment with room placement and configurations that you explained about in a previous post.

[Larry M]

Bruce, They are RCF Evox 12

[Bill Fitzmaurice]

Not as bad as Bose, but close. They have to cross at 180Hz because the 4" top drivers can't go lower. No tweeters equals poor high frequency dispersion. One T48 would equal four of those subs. Just sayin'...

[Larry M]

Ouch! lol well at least it’s better than Bose! I know what I have isn’t the best but I’m always looking to improve my sound and I would love to hear recommendations for a sound system that meets my needs.

I DJ mostly weddings so for me I have a few goals. Not in order of importance. They are all important.

1. It needs to be portable for two people. Some weddings are in barns and set up is in the loft up stairs.
2. Needs to sound good. To me this is full sounding and balanced on the dance floor even at high volume. No piercing highs and glass tapping lows but not so low it shakes grandmas glasses off.
3. Needs to look esthetically good and clean.
4. Well made and reliable. I like wood cabinets.

Did I miss anything that’s important that anyone can think of?

[Bill Fitzmaurice]

SLA Pro and T39.

[Seth]

I second the SLAP and T39 recommendation. Use white Duratex.

[Larry M]

Bill and Seth, Thank you for your input and advise. I have always wanted to actually build a speaker box from scratch. This project will be fun!

[Bruce Weldy]

Use white Duratex.

If you do, you'll have to get some custom made covers.

[himhimself]

Once you do a gig with horn loaded subs you'll be astounded how good they sound - and how much your party goers will love the sound without understanding why. They will feel the music like never before without the harshness and ear ringing afterward.

[madmallard]

That's 1.56 feet from cab edge to cab edge. That shouldn't be a problem. The port orientation doesn't matter.

possibly stupid question: with 4 boxes, cluster in a line or in a square?